Systems and methods for pre-cooling in hydrogen or helium liquefaction treatment

Abstract

Described herein is a system and process for pre-cooling a hydrogen or helium gas stream for liquefaction using liquid nitrogen with reduced energy consumption and liquid nitrogen usage. The system includes a stream of pressurized liquid nitrogen, at least one turboexpander, and at least one heat exchanger.

Description

Technical Field

[0001] This disclosure relates to a precooling process using liquid nitrogen in the liquefaction of hydrogen or helium. More specifically, the present disclosure relates to a method of precooling hydrogen or helium gas using a process based on the supply of liquid nitrogen, the method incorporating at least one turboexpander and one or more heat exchangers, which cooperate to reduce the amount of nitrogen required for precooling and the energy consumed in the precooling process.

Background Art

[0002] The liquefaction of hydrogen and helium requires a large consumption of energy. Hydrogen has the second lowest boiling point among all substances, with a boiling point of -253°C at atmospheric pressure. Only helium has a lower boiling point. The liquefaction process is divided into several stages such as hydrogen compression, precooling, and liquefaction. In the precooling stage of hydrogen liquefaction, hydrogen gas can be cooled from ambient temperature to approximately -191°C. Large-scale hydrogen liquefaction plants utilize liquid nitrogen supplied from related nitrogen / air liquefaction plants. The processes of hydrogen and helium liquefaction frequently use liquid nitrogen for the purpose of precooling in the liquefaction process. The use of liquid nitrogen reduces the overall energy requirement in the production of liquid hydrogen or liquid helium. Furthermore, the liquid nitrogen obtained for this use is produced separately with a considerable consumption of energy. As a means of precooling hydrogen or helium before liquefaction, the direct evaporation of liquid nitrogen, which was conventionally supplied at low pressure and low temperature for evaporation and superheat, requires a large temperature difference between the warm fluid of hydrogen or helium and the low-temperature nitrogen fluid.

[0003] Figure 5 shows an example of a conventional pre-cooling treatment of hydrogen gas with liquid nitrogen (500). Liquid nitrogen (LIN) is supplied in a flow (504), and hydrogen gas (warm or ambient temperature) is supplied in a flow (501). The liquid nitrogen flow (504) and the hydrogen gas flow (501) flow in opposite directions through a heat exchanger (502), yielding a cooled hydrogen gas flow (503) and a heated nitrogen gas flow (505). The state of the supplied liquid nitrogen is typical of that produced by a cryogenic air separation plant.

[0004] The pre-cooling process directly impacts the total energy required to liquefy hydrogen or helium. The energy required for pre-cooling, expressed in terms of the energy needed to produce the required liquid nitrogen, represents a significant portion of the total energy required to liquefy liquid hydrogen or helium. Recent research has focused on means to reduce the total energy required to liquefy hydrogen or helium, and to reduce the amount of liquid nitrogen needed, through various means of supplying pre-cooling and refrigeration. [Overview of the Initiative] [Means for solving the problem]

[0005] A method is disclosed for pre-cooling hydrogen or helium gas before liquefaction using a liquid nitrogen stream. This method includes the steps of: a) providing a pressurized liquid nitrogen stream containing liquid nitrogen at a pressure of about 15 bar(a) to about 70 bar(a); b) passing the pressurized liquid nitrogen stream and the partially cooled hydrogen or helium gas stream through a first heat exchanger that exchanges heat between the pressurized liquid nitrogen stream and the partially cooled hydrogen or helium gas stream to obtain a first partially heated nitrogen stream and a pre-cooled hydrogen or helium gas stream; c) passing the first partially heated nitrogen stream through one or more turbo expanders that reduce the temperature and pressure of the partially heated nitrogen stream to obtain a low-temperature nitrogen stream; and d) passing the low-temperature nitrogen stream through the first heat exchanger and the second heat exchanger to obtain a pre-cooled hydrogen or helium gas stream and a fully heated nitrogen gas stream. Step (d) may include the steps of passing a low-temperature nitrogen flow through a first heat exchanger that exchanges heat between a low-temperature nitrogen flow and a partially cooled hydrogen or helium gas flow to obtain a second partially heated nitrogen gas flow and a pre-cooled hydrogen or helium gas flow; and passing a second partially heated nitrogen gas flow through a second heat exchanger that exchanges heat between a second partially heated nitrogen gas flow and a warm hydrogen or warm helium gas flow to obtain a fully heated nitrogen gas flow and a partially cooled hydrogen or helium gas flow. The first and second heat exchangers may be separate devices or two parts within a single heat exchanger. The method may further include the step of utilizing an auxiliary refrigeration system connected to the second heat exchanger.

[0006] Step (a) may include supplying a liquid nitrogen stream produced at a saturation pressure of less than approximately 10 bar(a), followed by increasing the pressure of the liquid nitrogen stream to obtain a pressurized liquid nitrogen stream. Step (a) may include supplying a liquid nitrogen stream produced at a saturation pressure of less than approximately 10 bar(a); splitting the liquid nitrogen stream into a first portion and a second portion; and increasing the pressure of the first portion of the liquid nitrogen stream to obtain a pressurized liquid nitrogen stream. The second portion of the liquid nitrogen stream can pass through a first heat exchanger to obtain a third partially heated nitrogen stream. The third partially heated nitrogen stream can pass through a second heat exchanger to obtain a second fully heated nitrogen gas stream. The pressurized liquid nitrogen has a pressure of approximately 15 bar(a) to approximately 70 bar(a), or approximately 20 bar(a) to approximately 55 bar(a).

[0007] The pressurized liquid nitrogen stream may be split into a first pressurized liquid nitrogen stream and a second pressurized liquid nitrogen stream, which are then passed separately through a first heat exchanger for heat exchange between the first and second pressurized liquid nitrogen streams and a partially cooled hydrogen or helium gas stream.

[0008] a.) A step of supplying a liquid nitrogen stream produced at a saturation pressure of less than approximately 10 bar(a); b.) A step of leading a first portion of the liquid nitrogen stream to a first heat exchanger to obtain a first partially heated nitrogen stream; c.) A step of leading the first partially heated nitrogen stream to a second heat exchanger to obtain a first fully heated nitrogen gas stream; c.) A step of increasing the pressure of the second portion of the liquid nitrogen stream to obtain a pressurized liquid nitrogen stream at a pressure of approximately 15 bar(a) to approximately 70 bar(a); d.) A step of passing the pressurized liquid nitrogen stream and a partially cooled hydrogen or helium gas stream toward the first heat exchanger to obtain a second partially heated nitrogen gas stream and a pre-cooled hydrogen or helium gas stream; e.) A step of passing the second partially heated nitrogen gas stream through a second heat exchanger that exchanges heat between the second partially heated nitrogen gas stream and the warm hydrogen or warm helium gas stream to obtain a second fully heated nitrogen gas stream. Another method for pre-cooling hydrogen or helium gas using a liquid nitrogen flow is disclosed, comprising: f) obtaining a fully heated nitrogen gas flow and a partially cooled hydrogen or helium gas flow; e) obtaining a low-temperature nitrogen flow by passing the second fully heated nitrogen gas flow through one or more turbo expanders that reduce the temperature and pressure of the second fully heated nitrogen gas flow; f) obtaining a third partially heated nitrogen gas flow and a pre-cooled hydrogen or helium gas flow by passing the low-temperature nitrogen flow through a first heat exchanger that exchanges heat between the low-temperature nitrogen flow and the partially cooled hydrogen or helium gas flow; f) obtaining a third fully heated nitrogen gas flow and a partially cooled hydrogen or helium gas flow by passing the third partially heated nitrogen gas flow through a second heat exchanger that exchanges heat between the third partially heated nitrogen gas flow and a warm hydrogen or warm helium gas flow. Step (g) may include passing the second fully heated nitrogen flow through one or more compressors and one or more condensers before passing the second fully heated nitrogen flow through one or more turbo expanders. Step (g) may also include passing the second fully heated nitrogen flow through two turbo expanders connected in series. This method may further include utilizing an auxiliary refrigeration system connected to the second heat exchanger.

[0009] The pressurized liquid nitrogen flow may be split into a first pressurized liquid nitrogen flow and a second pressurized liquid nitrogen flow; the first pressurized liquid nitrogen flow and the second pressurized liquid nitrogen flow may pass separately through the first heat exchanger, and optionally through the second heat exchanger.

[0010] The method may include a system for recooling a second or third fully heated nitrogen gas flow, the recooling system comprising: i) passing the second or third fully heated nitrogen gas flow through a first compressor and a first cooler to obtain a compressed and cooled nitrogen gas flow, wherein the first compressor is connected to a second heat exchanger and a first cooler; ii) passing the compressed and cooled nitrogen gas flow through one or more turbo expanders; and iii) passing the turbo-expanded nitrogen gas flow through a second heat exchanger to obtain a fourth fully heated nitrogen gas flow. Step (ii) includes passing the compressed and cooled nitrogen gas flow through two turbo expanders connected in series.

[0011] A pre-cooling system using liquid nitrogen for hydrogen or helium liquefaction is also disclosed. This system may include a hot hydrogen or hot helium gas flow; a pressurized liquid nitrogen flow from a liquid nitrogen source; a heat exchanger; and at least one turbo expander connected to the heat exchanger and configured to lower the temperature of a partially heated nitrogen gas flow released from the heat exchanger. The heat exchanger may be configured to exchange heat between the pressurized liquid nitrogen flow and the hot hydrogen or hot helium gas flow to raise the temperature of the pressurized liquid nitrogen flow and lower the temperature of the hot hydrogen or hot helium gas flow to obtain a pre-cooled hydrogen or helium gas flow and a warm nitrogen gas flow. In another embodiment, the system includes: a first heat exchanger configured to exchange heat between a pressurized liquid nitrogen flow and a partially cooled hydrogen or helium gas flow to raise the temperature of the pressurized liquid nitrogen flow to obtain a partially heated nitrogen gas flow and to lower the temperature of the partially cooled hydrogen or helium gas flow; at least one turbo expander configured to lower the temperature of the partially heated nitrogen gas flow; and a second heat exchanger configured to exchange heat between the partially heated nitrogen gas flow and a warm hydrogen or warm helium gas flow to raise the temperature of the partially heated nitrogen gas flow to obtain a fully heated nitrogen gas flow and to lower the temperature of the warm hydrogen or warm helium gas flow.

[0012] The system may also include at least one compressor and at least one cooler configured to receive a flow of warm nitrogen gas released from a heat exchanger, at least one turbo expander configured to receive a flow of warm nitrogen gas after it has passed through the at least one compressor and at least one cooler, and / or optionally a valve connected to the turbo expander. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of a system for pre-cooling hydrogen gas using liquid nitrogen, first and second heat exchangers, a turbo expander, and auxiliary refrigeration. [Figure 2] This is a schematic diagram of a system for pre-cooling hydrogen gas using liquid nitrogen, first and second heat exchangers, a turbo expander, auxiliary refrigeration, and other components. [Figure 3] This is a schematic diagram of a system for pre-cooling hydrogen gas using liquid nitrogen, first and second heat exchangers, multiple turbo expanders, multiple compressors, multiple coolers, auxiliary refrigeration, and other components. [Figure 4] This is a schematic diagram of a system for pre-cooling hydrogen gas using liquid nitrogen, first and second heat exchangers, two turbo expanders, two compressors, two coolers, and other components. [Figure 5] This is a schematic diagram of a conventional system that pre-cools hydrogen or helium gas using liquid nitrogen. [Modes for carrying out the invention]

[0014] Processes disclosed herein have been developed to reduce, to some extent, the amount of liquid nitrogen required to pre-cool hydrogen or helium gas in the liquefaction process. These processes and pre-cooling systems employ further steps and apparatus to more fully utilize the amount of liquid nitrogen supplied to the pre-cooling system. That is, externally sourced liquid nitrogen is consumed at a lower flow rate compared to conventional pre-cooling systems. It is also understood that if liquid nitrogen is used to pre-cool other hydrogen or helium streams used in the liquefaction process (so-called recycled streams), means of reducing liquid nitrogen consumption there are also applicable.

[0015] In a method disclosed herein for pre-cooling hydrogen or helium gas using a liquid nitrogen stream, the liquid nitrogen feed is pressurized and supplies most of its cooling capacity in heat exchange with the hydrogen or helium gas, which heats the nitrogen; the heated nitrogen is then mechanically expanded to a low temperature and reintroduced for heat exchange with the hydrogen or helium. In practice, the supplied liquid nitrogen passes through the same heat exchanger a second time (in a loop), thus reducing the amount of liquid nitrogen required and the associated energy needed for its production. The energy cost for producing this reduced amount of liquid nitrogen is thus reduced. Since this cost is a significant component of the energy cost for producing liquid hydrogen or liquid helium, the overall cost of liquefaction is reduced, which is commercially significant. The cost of pre-cooling can be reduced by approximately 20% to approximately 50%.

[0016] As used herein, the term “mechanically expand” includes any device used to generate work by reducing the enthalpy of the fluid being expanded, such as a turbo expander or a reciprocating engine.

[0017] Conventional liquid nitrogen pre-cooling processes for hydrogen consume approximately 7 to 10 kg of liquid nitrogen per kg of liquefied hydrogen. The pre-cooling process disclosed herein may consume approximately 4 to 6 kg of liquid nitrogen, or approximately 4.30 to 5.35 kg, per kg of liquefied hydrogen. This represents a significant reduction in liquid nitrogen consumption compared to conventional processes.

[0018] A method for pre-cooling hydrogen or helium gas using a liquid nitrogen stream is disclosed, which utilizes an overall reduction in the amount of liquid nitrogen compared to conventional pre-cooling methods.

[0019] This method includes the step of preparing a pressurized liquid nitrogen stream that may have a pressure of about 15 bar(a) to about 70 bar(a), about 20 bar(a) to about 60 bar(a), or 20 bar(a) to about 50 bar(a). The pressurized liquid nitrogen may have a temperature of about -147 °C to about -196 °C, about -169 °C to about -195 °C, or about -189 °C to about -194 °C.

[0020] The pressurized liquid nitrogen may be supplied directly to the method disclosed herein. Alternatively, the liquid nitrogen may be supplied from an external source having a saturation pressure of about 1 bar(a) to about 10 bar(a), and this may then be pressurized by any means known in the art. The liquid nitrogen may be pressurized by utilizing a pump or by compressing to increase the pressure.

[0021] In one embodiment, the pressurized liquid nitrogen stream may be split into a first pressurized liquid nitrogen stream and a second pressurized liquid nitrogen stream, and each of the first pressurized liquid nitrogen stream and the second pressurized liquid nitrogen stream may be directed through a first heat exchanger to effect heat exchange between each of the first and second pressurized liquid nitrogen streams and a partially cooled hydrogen or helium gas stream. Two partially warmed nitrogen streams that have passed through the first heat exchanger separately may be combined into one stream before being directed through at least one turboexpander.

[0022] In one embodiment, a liquid nitrogen stream produced at a saturation pressure of less than about 10 bar(a) is supplied to the system and split into a first portion of the liquid nitrogen stream and a second (or remaining) portion of the liquid nitrogen stream. The first portion of the liquid nitrogen stream may have a pressure increased, for example, by a pump or by compression, by any means known in the art, to obtain a pressurized liquid nitrogen stream, and the second portion of the liquid nitrogen stream may be directed to a first heat exchanger separately from the path of the pressurized liquid nitrogen stream and then optionally to a second heat exchanger.

[0023] As used herein, "pump" means a mechanical device that increases the pressure of a liquid.

[0024] A warm hydrogen or warm helium gas stream is supplied for precooling and may be supplied from one or more hydrogen or helium feed streams or a recycled hydrogen or helium feed stream. The warm hydrogen gas stream may be produced from natural gas, electrolysis of water, or other chemical methods. The warm hydrogen or warm helium gas stream may be supplied from a source external to the liquefaction process or may be a recycle stream from another part of the process. The warm hydrogen gas stream may be at any pressure suitable for its final liquefaction. The warm hydrogen gas stream may have a pressure of about 20 bar(a) to about 80 bar(a), or about 20 bar(a) to about 40 bar(a), and / or a temperature of about 25°C to about 35°C. The warm hydrogen gas stream may have a composition of about 75% ortho and about 25% para spin isomers.

[0025] Ortho-para conversion of the hydrogen gas may be incorporated when the hydrogen gas is cooled. The ortho-para conversion may be carried out in a first heat exchanger and in a second heat exchanger, and the path of the heat exchanger(s) may optionally be filled with a catalyst for the feed hydrogen. The catalyst may be any known in the art for this purpose. This can improve the overall energy efficiency of the liquefaction process. The precooled hydrogen gas stream may have a temperature of about -173°C to about -196°C, about -180°C to about -196°C, or about -190°C to about -192°C, and / or a pressure of about 15 bar(a) to about 100 bar(a), or about 20 bar(a) to about 8 bar(a). The precooled hydrogen gas stream may be about 53% ortho and about 47% para.

[0026] As used herein, “heat exchanger” means any device capable of transferring thermal or cold energy from one medium to another, for example, between at least two distinct fluids. Heat exchangers include “direct heat exchangers” and “indirect heat exchangers.” Thus, a heat exchanger may be any suitable design, e.g., a parallel or counterflow heat exchanger, an indirect heat exchanger (e.g., a spiral heat exchanger, or a plate-fin heat exchanger such as a blazed aluminum plate-fin type), a direct contact heat exchanger, a shell-and-tube heat exchanger, a spiral type, a hairpin type, a core type, a core-and-kettle type, a printed circuit type, a double-tube type, or any other known type of heat exchanger.

[0027] As used herein, the first heat exchanger transfers energy between opposing flows during the cooling step of the process, while the second heat exchanger transfers energy between opposing flows during the heating step of the process. A pre-cooled hydrogen or helium gas flow exits the first heat exchanger, while a fully heated nitrogen gas flow exits the second heat exchanger. The first and second heat exchangers may be two parts of a single heat exchanger, or they may be two separate heat exchangers. If the first and second heat exchangers are two parts of a single heat exchanger, the heat exchanger may include, but are not limited to, outlet points of valves at various locations in the unit for the flow through it.

[0028] As used herein, the term “indirect heat exchange” means that two fluids are in a heat exchange relationship without physical contact or mixing with each other. Core-in-kettle heat exchangers and blazed aluminum plate-fin heat exchangers are examples of devices that facilitate indirect heat exchange.

[0029] The next step involves passing the partially heated nitrogen flow through at least one turbo expander, which reduces the temperature and pressure of the partially heated nitrogen flow to obtain a low-temperature nitrogen flow. The turbo expander may be connected to a first heat exchanger by any means known in the art. The exhaust from the turbo expander may flow to the first heat exchanger. The turbo expander may include brakes such as a blower, fan, or oil pump for circulation and cooling to dissipate energy. The turbo expander may be connected to a compressor to capture the energy generated by the turbo expander.

[0030] By passing a warm nitrogen flow through one turbo expander, it is possible to cool it by approximately 30° to 130° or approximately 50° to 100°, and / or reduce its pressure by approximately 2 bar to 100 bar, 4 bar to 60 bar, or approximately 30 bar to 50 bar. By passing the flow through a second turbo expander connected in series with the first turbo expander, the temperature and pressure of the flow can be further reduced. The first turbo expander may be connected to the second turbo expander.

[0031] As used herein, “turbo expander” refers to any device, but not limited to, typically an inward radial flow device used in cryogenic processing, that is used to achieve a temperature reduction by causing a pressure drop, while simultaneously generating useful energy that can be extracted or captured to assist the required cooling process in performing its work. The turbo expander generates mechanical energy by rotation using the energy of the expanded gas. The turbo expander rotates at high speed and then the energy can be transferred via a shaft to a compressor, which recovers the energy by compressing another feed gas flow. This process can then pressurize the feed gas flow back to the compressor, thereby supplying useful energy back to the system.

[0032] Depending on the circumstances, this method may include the step of passing a partially heated nitrogen flow through at least one compressor and at least one turbo expander in any order to obtain a low-temperature nitrogen flow returning through a first or second heat exchanger. This method may also include the step of passing a partially heated nitrogen flow through two to five compressors and two to five turbo expanders to obtain a low-temperature nitrogen flow returning through a first or second heat exchanger. This method may also include the step of passing a partially heated nitrogen flow through two to five compressors, two to five turbo expanders, and two to five coolers to obtain a low-temperature nitrogen flow returning through a first heat exchanger. The same number of coolers as the number of compressors may be used in the process. One or more of the turbo expanders may be connected to one compressor by a shaft.

[0033] As used herein, “cooler” means any water or air cooler known in the art that removes heat from a system, such as a fin-fan unit, shell-and-tube unit, or plate cooler that uses a water or brine system to cool a process flow from a high temperature to near ambient temperature. The step of passing the flow through a cooler can lower the temperature of the flow by about 40°C to about 100°C.

[0034] When a low-temperature nitrogen stream is passed through the first heat exchanger, this creates a loop in the pre-cooling process, which is the second pass of the nitrogen stream through the first heat exchanger. This allows the same initially supplied nitrogen to be recycled and used counter-flow to cool a hydrogen or helium gas stream a second time through the first heat exchanger. The low-temperature nitrogen stream may pass through a valve before passing through the first heat exchanger a second time in the pre-cooling process. Turbo expanders have a limited range of pressure ratios (inlet pressure / outlet pressure), and therefore, if necessary, a valve may be added to the system to further reduce the pressure instead of adding, for example, a second turbo expander. Thus, when using a valve, there is a pressure loss in the nitrogen stream before and after the valve. The valve can reduce the temperature and pressure of the nitrogen stream and increase the proportion of gas in the nitrogen stream.

[0035] After passing through the second heat exchanger, the fully heated nitrogen gas flow may have a temperature of approximately 15°C to approximately 30°C, or approximately 20°C to approximately 28°C, and a pressure of approximately 0.5 bar(a) to approximately 2 bar(a), or approximately 1 bar(a) to approximately 2 bar(a). The fully heated nitrogen gas flow may be reintroduced to the second heat exchanger via another processing loop including at least one turbo expander and optionally at least one compressor for pressurization and cooling. The fully heated nitrogen gas flow may be reintroduced to the first heat exchanger and then to the second heat exchanger via another processing loop including at least one turbo expander and optionally at least one compressor for pressurization and cooling.

[0036] A pre-cooling system using liquid nitrogen for hydrogen or helium liquefaction is also disclosed. The system may include: a flow of warm hydrogen or warm helium gas; a flow of pressurized liquid nitrogen from a source of liquid nitrogen; a first heat exchanger configured to exchange heat between the pressurized liquid nitrogen flow and a partially cooled hydrogen or helium gas flow to raise the temperature of the pressurized liquid nitrogen flow to obtain a partially heated nitrogen gas flow and lower the temperature of the partially cooled hydrogen or helium gas flow; at least one turbo expander configured to lower the temperature of the partially heated nitrogen gas flow; and a second heat exchanger configured to exchange heat between the partially heated nitrogen gas flow and a warm hydrogen or warm helium gas flow to raise the temperature of the partially heated nitrogen gas flow and lower the temperature of the warm hydrogen or warm helium gas flow. The first or second heat exchanger may be connected to one turbo expander. The pre-cooling system may include a valve connected to one turbo expander. The valve may be configured to reduce the pressure of the nitrogen gas flow.

[0037] The pre-cooling system may include at least one compressor and at least one cooler, and optionally at least one turbo expander configured to receive a fully heated nitrogen gas flow after passing through a second heat exchanger. The pre-cooling system may include at least one turbo expander configured to receive a warm nitrogen gas flow after passing through at least one compressor and at least one cooler. The pre-cooling system may include 1 to 4 compressors, 1 to 4 coolers, and 1 to 4 turbo expanders configured to receive a fully heated nitrogen gas flow after passing through a second heat exchanger, with each compressor connected to a cooler and the 1 to 4 turbo expanders connected in the system after the compressors and coolers.

[0038] A pre-cooling system using liquid nitrogen for hydrogen or helium liquefaction is also disclosed, the system comprising: a hot hydrogen or hot helium gas flow; a pressurized liquid nitrogen flow from a source of liquid nitrogen; a heat exchanger configured to exchange heat between the pressurized liquid nitrogen flow and the hot hydrogen or hot helium gas flow to raise the temperature of the pressurized liquid nitrogen flow to obtain a hot nitrogen gas flow, and to lower the temperature of the hot hydrogen or hot helium gas flow to obtain a pre-cooled hydrogen or helium gas flow; and at least one turbo expander connected to the heat exchanger and configured to lower the temperature of a partially heated nitrogen gas flow released from the heat exchanger. The pre-cooling system may also include at least one compressor and at least one cooler configured to receive the hot nitrogen gas flow after it has passed through the heat exchanger, and optionally at least one turbo expander configured to receive the hot nitrogen gas flow after it has passed through the at least one compressor and at least one cooler. The pre-cooling system may also include a valve connected to the turbo expander configured to reduce the pressure of the nitrogen gas flow.

[0039] Systems and processes relating to the precooling of hydrogen or helium gas using a liquid nitrogen stream are described herein. Specific embodiments of this disclosure include those shown in the following paragraphs, which are described with reference to the figures. Some configurations are described with particular reference to only one figure (e.g., Figures 1, 2, 3, 4), but they are similarly applicable to other figures and may be used in combination with other figures or the preceding discussion.

[0040] Figures 1–4 show non-limiting examples of various systems and processes 100, 200, 300, 400 for pre-cooling hydrogen or helium gas using a liquid nitrogen stream in accordance with this disclosure. The liquid nitrogen stream (LIN) 104, 204, 304, 404 is supplied from any LIN supply system, e.g., one or more tankers, tanks, pipelines, etc., or any combination thereof. The system includes at least one heat exchanger, e.g., first heat exchangers 131, 231, 331, 431 and second heat exchangers 130, 230, 330, 430. These systems include pumps 132, 232, 332, 432 for receiving the liquid nitrogen stream and increasing the pressure to create a pressurized liquid nitrogen stream 105, 250, 306, 406. The pressurized liquid nitrogen stream may be divided into more than one stream, e.g., two streams 250, 240. Hot hydrogen or hot helium gas is supplied from any source of flows 101, 201, 301, 401, which pass through a second heat exchanger to obtain partially cooled hydrogen or helium gas flows 102, 202, 302, 402, which pass through a first heat exchanger for further cooling to obtain pre-cooled hydrogen or helium gas flows 103, 203, 303, 403.

[0041] Figure 1 shows a system 100 for pre-cooling hydrogen or helium gas using a liquid nitrogen flow. A liquid nitrogen flow 104 is guided through a pump 132 to increase its pressure. The pressurized liquid nitrogen flow 105 passes through a first heat exchanger 131 that transfers energy between the pressurized liquid nitrogen flow 105 and a partially cooled hydrogen or helium gas flow 102 flowing in the opposite direction, thereby increasing the temperature of the nitrogen flow. The partially heated nitrogen gas flow 106 then passes through a turbo expander 133 to obtain a low-temperature nitrogen gas flow 107 having a lower pressure and lower temperature than flow 106. It is envisioned that the system may include more than one turbo expander connected in series to reduce the temperature and pressure of the nitrogen flow before it re-enters the first heat exchanger. The disclosure includes another embodiment in which multiple turbo expanders, such as two, three, or four, may be connected in series at specified locations of each turbo expander when it is necessary to further reduce the flow pressure.

[0042] The low-temperature nitrogen gas flow 107 then completes the loop by passing through the first heat exchanger, and during the second pass of the nitrogen gas flow through the first heat exchanger, energy is transferred between the partially cooled hydrogen or helium gas flow 102 and the low-temperature nitrogen gas flow 107 to obtain the partially heated nitrogen gas flow 108 and the pre-cooled hydrogen or helium gas flow 103.

[0043] The partially heated nitrogen gas flow 108 then passes through two heat exchangers 130, where energy is transferred between the warm hydrogen or warm helium gas flow 101 and the partially heated nitrogen gas flow 108 to produce a fully heated nitrogen gas flow 109 and a partially cooled hydrogen or helium gas flow 102, which then pass through one heat exchanger 131.

[0044] The second heat exchanger 130 may include auxiliary refrigeration, indicated here as propene flows 114, 115. The liquid propene flow 114 passes through the second heat exchanger, exchanging heat between the auxiliary refrigeration and the hot hydrogen or hot helium gas flow 101, and exits as a gaseous propene flow 115. The second heat exchanger may include auxiliary refrigeration connected to the second heat exchanger. The auxiliary refrigeration supplements the coolant for the pre-cooling process and may be supplied from any other known source of refrigeration. The auxiliary refrigeration may be vapor compression refrigeration, absorption refrigeration, mixed refrigerant refrigeration, or any other means known to extract heat from the hot hydrogen or hot helium gas flow. The auxiliary refrigeration may consist of one refrigeration flow, or two refrigeration flows, one or different. The auxiliary refrigeration may be a propene refrigeration flow that supplies a liquid flow at a temperature of about -20°C to -50°C and exits the system as a gaseous flow.

[0045] Having described embodiments of the present disclosure, further embodiments will now be described. Figure 2 shows a system 200 for pre-cooling hydrogen or helium gas using a liquid nitrogen flow. In Figure 2, the liquid nitrogen is pumped to high pressure and, after evaporation and superheating for cooling the hydrogen, returns through a turbo expander for further cooling of the hydrogen. Valves 235 are shown between flows 208 and 209 to satisfy the aerodynamic limitations of the turbo expander as needed. Auxiliary refrigeration is provided as part of the cooling process, for example, from propene vapor-compression refrigeration, at a temperature level significantly higher than that of the liquid nitrogen.

[0046] The system in Figure 2 is configured such that the diverted pressurized liquid nitrogen flows 240 and 250 pass through the first heat exchanger 231, thereby heating the diverted pressurized liquid nitrogen flows 240 and 250 so that the pressure remains substantially constant, for example, the pressure difference can be less than approximately 1 bar(a). It is assumed that the flows can exit through any desired outlet to achieve the desired heat exchange, but each of the diverted partially heated nitrogen flows 241 and 251 exits the first heat exchanger through a different outlet. The diverted partially heated nitrogen flows 241 and 251 are then merged to form a single partially heated nitrogen flow 207, which is passed through a turbo expander 233 connected to a brake 234. As it passes through the turbo expander, one of the heated nitrogen flows 207 is cooled, the pressure decreases, and the amount of liquid in the flow increases, for example, from approximately 0% to approximately 6% in flow 207 and approximately 10% in flow 208. Valve 235 is located between the turbo expander 233 and the first heat exchanger 231, which reduces the temperature and pressure of the low-temperature nitrogen flow 208 before it returns to the first heat exchanger and passes through the first heat exchanger a second time. By passing through the first heat exchanger 231, the low-temperature, low-pressure nitrogen flow 209 is heated. As it passes through the first heat exchanger 231, the liquid in the low-temperature, low-pressure nitrogen flow 209 vaporizes, resulting in a partially heated nitrogen gas flow 210 with approximately 0% liquid. The partially heated nitrogen gas flow is then guided to pass through the second heat exchanger 230, where the partially heated nitrogen gas flow 210 is heated and the warm hydrogen or warm helium gas flow 201 is cooled to obtain a fully heated nitrogen gas flow 211 and a partially cooled hydrogen or helium gas flow 202. The figure shows that the partially heated nitrogen gas flow 210 exits the first heat exchanger 231 and then enters the second heat exchanger 230. However, if the first and second heat exchangers are two parts of one unit, it can be understood that the flow remains within one heat exchanger unit while flowing directly from the first heat exchanger to the second heat exchanger. The second heat exchanger 230 may include auxiliary refrigeration such as propene flows 214 and 215. The liquid propene flow 214 passes through the second heat exchanger 230, exchanging heat between the auxiliary refrigeration and the warm hydrogen or warm helium gas flow 201, and as a result, the liquid propene flow 214 exits the second heat exchanger as gaseous propene flow 215. Table 2 includes a list of the flows and apparatus shown in Figure 2, as well as the characteristics of each flow.The liquid nitrogen consumption, calculated by dividing the LIN supply flow rate by the pre-cooled hydrogen flow rate (i.e., the flow rate of 204 / 203), is 5.18 kg LIN / kg LH2.

[0047] [Table 1]

[0048] Figure 3 shows a process and system 300 for pre-cooling hydrogen or helium gas using a liquid nitrogen flow, four turbo expander-compressors, and auxiliary refrigeration supplied at -26°C to -46°C. The system in Figure 3 is configured such that the liquid nitrogen flow 304 is diverted so that a portion of the liquid nitrogen supply passes through pump 332 to obtain a pressurized liquid nitrogen flow 306. The other portion of the liquid nitrogen supply 305 passes through valve 384, and the flow 325 then enters a first heat exchanger 331, where it is heated to obtain a first partially heated nitrogen gas flow 326, which is then passed through a second heat exchanger for further heating to obtain a first fully heated nitrogen gas flow 327. The pressurized liquid nitrogen flow 306 also passes through the first heat exchanger 331, thereby increasing the temperature of the pressurized liquid nitrogen flow 306, while the pressure remains substantially constant, for example, the pressure difference can be less than about 1 bar(a). The second partially heated nitrogen gas flow 322 then passes through a second heat exchanger 330 for further heating, exiting through a central outlet to obtain nitrogen gas flow 307, which passes through turbo expanders 333, 334, each connected to compressors 335, 336, to obtain nitrogen gas flows 308, 309. The turbo expanders may be designed to drive compressors, pumps, hydraulic brakes, or any other similar power-consuming devices that extract energy from the system 300. As it passes through the first turbo expander 333, nitrogen gas flow 307 is cooled to become a low-temperature nitrogen gas flow 308. As it passes through the second turbo expander 334, low-temperature nitrogen gas flow 308 is cooled to become a low-temperature, low-pressure nitrogen gas flow 309. Each turbo expander reduces the pressure of the nitrogen flow passing through it. To reduce the temperature and pressure of the low-temperature, low-pressure nitrogen flow before it returns to the first heat exchanger and passes through the first heat exchanger a second time, a valve (not shown) may be provided between the second turbo expander and the first heat exchanger. After passing through the first heat exchanger 331, the third partially heated nitrogen gas flow 310 then passes through the second heat exchanger 330, where the third partially heated nitrogen gas flow 310 is heated and the warm hydrogen gas flow 301 is cooled to obtain a fully heated nitrogen gas flow 311 and a partially cooled hydrogen gas flow 302.The second heat exchanger 330 may include auxiliary refrigeration such as two auxiliary refrigeration systems as shown, including a first auxiliary refrigeration system including propene flows 350, 351 and a second auxiliary refrigeration system including propene flows 360, 361. In these auxiliary refrigeration systems, the liquid propene flows 350, 360 pass through a second heat exchanger that exchanges heat between the propene flows and a hot hydrogen gas flow 301, and as a result the liquid propene flows 350, 360 exit the second heat exchanger as gaseous propene flows 351, 361.

[0049] In Figure 3, the fully heated nitrogen gas flow 311 passes through four sets of compressors 335, 336, 337, 338, followed by coolers 382, ​​383, 381, 380, and then through the third and fourth turbo expanders 339, 340. It is assumed that any number of compressors and coolers (e.g., 1 to 6 sets) and any number of turbo expanders (e.g., 1 to 4 units) can be incorporated into the system. The compressors and subsequent coolers remove the heat of compression by ambient air, cooling water, or brine. Nitrogen flow 311 passes through the compressor, nitrogen flow 312 passes through the cooler, nitrogen flow 313 passes through the compressor, nitrogen flow 314 passes through the cooler, nitrogen flow 315 passes through the compressor, nitrogen flow 316 passes through the cooler, nitrogen flow 317 passes through the compressor, nitrogen flow 318 passes through the cooler, and nitrogen flows 319 and 320 pass through the turbo expander. After that, nitrogen gas flow 321 passes through the second heat exchanger 330, and fully heated nitrogen gas flow 323 is combined with fully heated nitrogen gas flow 327 to obtain a combined fully heated nitrogen gas flow 324.

[0050] Table 3 includes a list of the flows and equipment shown in Figure 3, as well as the characteristics of each flow. The liquid nitrogen consumption, calculated by dividing the LIN supply flow rate by the pre-cooled hydrogen flow rate, is 4.30 kg LIN / kg LH2.

[0051] [Table 2]

[0052] [Table 3]

[0053] Figure 4 shows a process and system 400 for pre-cooling hydrogen or helium gas using a liquid nitrogen flow, where the system includes two sets of turbo expander-compressor combinations for pre-cooling without an auxiliary refrigeration unit. The system in Figure 4 is configured such that a liquid nitrogen supply is split into two flows, with the first portion of the liquid nitrogen supply passing through a pump 432 to obtain a pressurized liquid nitrogen flow 406. The other portion of the liquid nitrogen supply 405 passes through a first heat exchanger 431, where it is heated and vaporized to obtain a first partially heated nitrogen gas flow 421, which then passes through a second heat exchanger for further heating to obtain a first fully heated nitrogen gas flow 422. The pressurized liquid nitrogen flow 406 is divided into two pressurized liquid nitrogen flows 409 and 407, each passing through a first heat exchanger 431 and exiting from a different outlet, thereby increasing the temperature of the pressurized liquid nitrogen flow while keeping the pressure substantially constant, for example, with a pressure difference of less than approximately 1 bar(a), and then joining two partially heated nitrogen gas flows 411. The two partially heated nitrogen gas flows 411 then pass through a second heat exchanger 430 for further heating to obtain a fully heated nitrogen gas flow 412. In this example, the fully heated nitrogen gas flow 412 passes through two sets of compressors 434 and 436 followed by coolers 481 and 480, and then through turbo expanders 435 and 433, each of which is connected to one of the compressors 434 and 436. It is assumed that any number of sets of compressors and coolers (e.g., 1 to 6 sets) followed by any number of turbo expanders (e.g., 1 to 4 units) can be incorporated into the system. After flow 412 passes through the compressor, flow 413 passes through the cooler, flow 414 passes through the compressor, flow 415 passes through the cooler, flow 416 passes through the turbo expander, and flow 417 passes through the turbo expander, the low-temperature, low-pressure nitrogen gas flow 418 passes through the first heat exchanger 431 to obtain another partially heated nitrogen gas flow 419, and then passes through the second heat exchanger 430 to obtain a fully heated nitrogen gas flow 420, which is combined with flow 422 to obtain a combined fully heated nitrogen gas flow 423.

[0054] Table 4 includes a list of the flows and equipment shown in Figure 4, as well as the characteristics of each flow. The liquid nitrogen consumption, calculated by dividing the LIN supply flow rate by the pre-cooled hydrogen flow rate, is 5.35 kg LIN / kg LH2.

[0055] [Table 4]

[0056] The conventional pre-cooling process is shown in Figure 5 and described above. Table 5 includes a list of the flows and apparatus shown in Figure 5, as well as the characteristics of each flow. By dividing the flow rate of the liquid nitrogen flow 504 by the flow rate of the pre-cooled hydrogen flow 503, the liquid nitrogen requirement is 7.28 kg of liquid nitrogen per 1 kg of hydrogen supply (7.28 kg LIN / kg LH2), where the hydrogen also undergoes ortho-para conversion.

[0057] [Table 5]

[0058] While various embodiments and specific preferred embodiments of the Disclosure are described herein, those skilled in the art will recognize that changes and modifications may be made to them without departing from the spirit of the Disclosure, and that such changes and modifications are intended to include any such changes and modifications that fall within the true scope of the Disclosure.

Claims

1. A method for pre-cooling hydrogen or helium gas using a liquid nitrogen stream, a. Providing a pressurized liquid nitrogen stream containing liquid nitrogen at a pressure of 15 bar(a) to 70 bar(a); b. A first heat exchanger that exchanges heat between a pressurized liquid nitrogen flow and a partially cooled hydrogen or helium gas flow, passing the pressurized liquid nitrogen flow and the partially cooled hydrogen or helium gas flow through it to obtain a first partially heated nitrogen flow and a pre-cooled hydrogen or helium gas flow; c. A step of obtaining a low-temperature nitrogen flow by passing the first partially heated nitrogen flow through one or more turbo expanders that reduce the temperature and pressure of the partially heated nitrogen flow; d. The step of passing the low-temperature nitrogen flow through the first heat exchanger and the second heat exchanger to obtain the pre-cooled hydrogen or helium gas flow and the fully heated nitrogen gas flow. Includes, A method wherein the first heat exchanger and the second heat exchanger are separate devices.

2. The method according to claim 1, wherein step (d) is the step of passing the low-temperature nitrogen flow through the first heat exchanger, which exchanges heat between the low-temperature nitrogen flow and the partially cooled hydrogen or helium gas flow, to obtain a second partially heated nitrogen gas flow and the pre-cooled hydrogen or helium gas flow; and passing the second partially heated nitrogen gas flow through the second heat exchanger, which exchanges heat between the second partially heated nitrogen gas flow and the warm hydrogen or warm helium gas flow, to obtain a fully heated nitrogen gas flow and the partially cooled hydrogen or helium gas flow.

3. The method according to claim 1 or claim 2, wherein the pressurized liquid nitrogen has a pressure of 20 bar(a) to 55 bar(a).

4. The method according to any one of claims 1 to 3, wherein step (a) is the step of supplying a liquid nitrogen stream produced at a saturation pressure of less than 10 bar(a); and the step of increasing the pressure of the liquid nitrogen stream to obtain the pressurized liquid nitrogen stream.

5. The method according to any one of claims 1 to 4, wherein step (a) is to supply a liquid nitrogen stream produced at a saturation pressure of less than 10 bar(a); to divide the liquid nitrogen stream into a first portion and a second portion; and to increase the pressure of the first portion of the liquid nitrogen stream to obtain the pressurized liquid nitrogen stream.

6. The method according to claim 5, further comprising the step of passing the second portion of the liquid nitrogen flow through the first heat exchanger to obtain a third partially heated nitrogen flow.

7. The method according to claim 6, further comprising the step of guiding the third partially heated nitrogen flow through the second heat exchanger to obtain a second fully heated nitrogen gas flow.

8. The method according to any one of claims 1 to 7, further comprising the step of utilizing an auxiliary refrigeration system connected to the second heat exchanger.

9. The method according to claim 2, wherein the pressurized liquid nitrogen flow is divided into a first pressurized liquid nitrogen flow and a second pressurized liquid nitrogen flow, the first pressurized liquid nitrogen flow and the second pressurized liquid nitrogen flow are passed separately through the first heat exchanger, and heat exchange takes place between the first and second pressurized liquid nitrogen flows and the partially cooled hydrogen or helium gas flow.

10. The method according to any one of claims 1 to 9, wherein step (c) includes passing the first partially heated nitrogen stream through one or two turbo expanders.

11. The method according to any one of claims 1 to 9, wherein step (c) includes passing the first partially heated nitrogen stream through one or more compressors before passing it through the one or more turbo expanders.

12. The method according to any one of claims 9 to 11, further comprising the step of utilizing an auxiliary refrigeration system connected to the second heat exchanger.

13. A method for pre-cooling hydrogen or helium gas using a liquid nitrogen stream, a. The step of supplying a liquid nitrogen stream produced at a saturation pressure of less than 10 bar(a); b. The step of guiding the first portion of the liquid nitrogen flow to the first heat exchanger to obtain a first partially heated nitrogen flow; c. The step of guiding the first partially heated nitrogen flow to a second heat exchanger to obtain a first fully heated nitrogen gas flow; d. The step of increasing the pressure of the second portion of the liquid nitrogen flow to obtain a pressurized liquid nitrogen flow with a pressure of 15 bar(a) to 70 bar(a); e. The step of passing the pressurized liquid nitrogen flow and the partially cooled hydrogen or helium gas flow toward the first heat exchanger to obtain a second partially heated nitrogen gas flow and a pre-cooled hydrogen or helium gas flow; f. The step of passing the second partially heated nitrogen gas flow through the second heat exchanger, which exchanges heat between the second partially heated nitrogen gas flow and the warm hydrogen or warm helium gas flow, to obtain a second fully heated nitrogen gas flow and the partially cooled hydrogen or helium gas flow; g. A step of obtaining a low-temperature nitrogen flow by passing the second fully heated nitrogen gas flow through one or more turbo expanders that reduce the temperature and pressure of the second fully heated nitrogen gas flow; h. The first heat exchanger, which exchanges heat between the low-temperature nitrogen flow and the partially cooled hydrogen or helium gas flow, is given a third partially heated nitrogen gas flow and a pre-cooled hydrogen or helium gas flow by passing the low-temperature nitrogen flow through it; i. The second heat exchanger, which exchanges heat between the third partially heated nitrogen gas flow and the warm hydrogen or warm helium gas flow, passes the third partially heated nitrogen gas flow through it to obtain a third fully heated nitrogen gas flow and the partially cooled hydrogen or helium gas flow. Methods that include...

14. The method according to claim 13, wherein step (g) includes passing the second fully heated nitrogen flow through one or more compressors and one or more coolers before passing the second fully heated nitrogen flow through one or more turbo expanders.

15. The method according to claim 13, wherein step (g) includes passing the second fully heated nitrogen stream through two turbo expanders connected in series.

16. The method according to any one of claims 13 to 15, wherein the pressurized liquid nitrogen flow is divided into a first pressurized liquid nitrogen flow and a second pressurized liquid nitrogen flow; and the first pressurized liquid nitrogen flow and the second pressurized liquid nitrogen flow pass through the first heat exchanger separately.

17. The method according to any one of claims 13 to 16, wherein the first heat exchanger and the second heat exchanger are separate devices.

18. The method according to any one of claims 13 to 16, wherein the first heat exchanger and the second heat exchanger are parts of a single heat exchanger.

19. The method according to any one of claims 13 to 18, further comprising the step of utilizing an auxiliary refrigeration system connected to the second heat exchanger.

20. A method further comprising a system for recooling the second or third fully heated nitrogen gas flow, wherein the recooling system is i. A step of passing the second or third fully heated nitrogen gas flow through a first compressor and a first cooler to obtain a compressed and cooled nitrogen gas flow, wherein the first compressor is connected to the second heat exchanger and the first cooler; ii. The step of passing the compressed and cooled nitrogen gas flow through one or more turbo expanders to form a turbo-expanded nitrogen gas flow; iii. The step of passing the turbo-expanded nitrogen gas flow through the second heat exchanger to obtain a fourth fully heated nitrogen gas flow. The method according to any one of claims 13 to 18, including the method described in any one of claims 13 to 18.

21. The method according to claim 20, wherein step (ii) includes passing the compressed and cooled nitrogen gas stream through two turbo expanders connected in series.

22. A pre-cooling system that uses liquid nitrogen for hydrogen or helium liquefaction, With a stream of hot hydrogen or hot helium gas; Pressurized liquid nitrogen flow from a liquid nitrogen supply source; A heat exchanger configured to exchange heat between the pressurized liquid nitrogen flow and the warm hydrogen or warm helium gas flow to raise the temperature of the pressurized liquid nitrogen flow to obtain a warm nitrogen gas flow, and to lower the temperature of the warm hydrogen or warm helium gas flow to obtain a pre-cooled hydrogen or helium gas flow; Connected to the heat exchanger and configured to reduce the temperature of the partially heated nitrogen gas flow released from the heat exchanger, at least one turbo expander Includes, A pre-cooling system further comprising at least one compressor and at least one cooler configured to receive the flow of warm nitrogen gas discharged from the heat exchanger.

23. The pre-cooling system according to claim 22, further comprising at least one turbo expander configured to receive the warm nitrogen gas flow after passing through the at least one compressor and the at least one cooler.

24. The pre-cooling system according to claim 22, further comprising a valve connected to the turbo expander, configured to reduce the pressure of the nitrogen gas flow.

25. A pre-cooling system using liquid nitrogen for hydrogen or helium liquefaction, With a stream of hot hydrogen or hot helium gas; Pressurized liquid nitrogen flow from a liquid nitrogen supply source; A first heat exchanger configured to exchange heat between the pressurized liquid nitrogen flow and a partially cooled hydrogen or helium gas flow to raise the temperature of the pressurized liquid nitrogen flow to obtain a partially heated nitrogen gas flow, and to lower the temperature of the partially cooled hydrogen or helium gas flow; A turbo expander configured to reduce the temperature of the partially heated nitrogen gas flow; A second heat exchanger is configured to exchange heat between the partially heated nitrogen gas flow and the hot hydrogen or hot helium gas flow to raise the temperature of the partially heated nitrogen gas flow to obtain a fully heated nitrogen gas flow and to lower the temperature of the hot hydrogen or hot helium gas flow. Includes, A pre-cooling system further comprising at least one compressor and at least one cooler configured to receive the fully heated nitrogen gas flow after passing through the second heat exchanger.

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